Man hits 40. Aaaargh! In a panic- riddled, apoplectic haze, he quits his dreary 9 to 5er, dumps his gravity-challenged other half and disappears off into the sunset with a firm-breasted 21-year-old ex-pole dancer attached to the back of his spanking new Harley.

Midlife crisis. It happens to the best of us. Sadly, the reality of the experience is generally not half as lurid, decadent and fun as this archetype might have you believe. More alarming still, it's no longer just fortysomethings who are suffering. The contemporary midlife crisis strikes younger, harder and in a completely different way.

We are, increasingly, a nation of singles with sky-high expectations, disinclined to shackle ourselves to precisely the things your traditional midlife crisis merchant ditches - the family unit, the office job, the suburban semi - which, in turn, has affected the expression of the new midlife crisis.

Currently, more people prefer to live alone, outnumbering traditional family households - 55 per cent of Londoners, for example, are living solo. Women, especially, are electing to live life now and give birth later, if at all. The birth rate has hit an all-time low; by 2007 there will be more pensioners kicking about than kids under 16, and one in five women worldwide is delaying having her first baby until the age of 35. Obviously, there's far too much self-exploration and wild-eyed embracing of life to be pursued beforehand. But then what?

Introducing the latest incarnation of the midlife crisis, in which thirtysomethings trade a life of feckless hedonism for the single-minded quest for domesticity. Justine Thornton, 33, is a classic example. She gave birth to her first child two months ago, after years of living a single life, boozing hard and going clubbing. She met her partner a year ago, just around the time she first started questioning her life's purpose. 'Sometimes I thank God that my son came along when he did, before I did permanent damage to myself,' she says. 'I had only myself to think about before - emotional needs, tension releases, getting pissed.

I was spoilt. Time alone now is something I appreciate a lot more.'

The modern, premature midlife crisis is fast becoming the reverse of the previous generation's experience, where the overload of responsibility led to the desire for freedom and crazed excursion into rediscovering independence.

This rabid crowd of carefree singletons, now well into their middle youth, find themselves hankering to be tamed, wishing to trade in their dancing shoes and well-oiled livers for a solid dose of stability and family life.

Music journalist Danny Jones is 37 and, despite having had several long-term relationships, has not yet been able to locate Ms Right. His midlife crisis is hitting hard and he's ill-prepared to deal with it. Never-ending sessions down the pub, drinking and taking drugs with his mates had, unsurprisingly, inspired one girlfriend after another to do a runner. 'I spent most of my twenties boozing and getting high in clubs,' he admits.

'I told myself I would sort myself out when I reached 30. I got there and nothing changed - I carried on going down the pub and doing cocaine, because it was a laugh. Now I'm 37 and still doing it, but it's become more habit than anything. I feel permanently paranoid - I just can't seem to shake it off.'

To Danny, blissful domesticity is beginning to seem like a comfortable alternative to rehab. For many, the transition to a quieter, more settled life has become a path speckled with potholes - an inability to adapt to the realms of coupledom, fuelled by society's obsession with utopia. 'Having it all' has come to mean that, now, we can marry domestic responsibilities with the bacchanalia of our youth. Popular culture endorses that notion, along, inevitably, with the suggestion that if we don't pull it off, we've failed.

At 35, Stacey Arnold is director of a leading advertising agency. Her career is blossoming and she is financially self-sufficient - but her personal life is suffering. 'I've enjoyed years of being single, having thrown myself into my career. I now want to settle down,' she explains. 'I meet guys but they never seem to meet the mark, and at the first sign of trouble I'm out. I'm starting to believe my perfect match just isn't out there. The thought of being alone for ever almost paralyses me with fear.'

This form of crisis has become a growing topic for a multitude of therapists and counsellors. 'More and more of my clients are having this trauma, and the government is partly to blame,' states Relate counsellor Denise Knowles. 'It has marketed certain careers - such as working in academia and finance - as being the only ones that reap success, and this induces a fear of failure, which has a knock-on effect on relationships.' Our expectations of ourselves and others, and of ourselves in relation to others, are phenomenal. Dissatisfaction and aspiration within the domain of our professional lives have influenced what successful people like Stacey demand and expect from their personal relationships - which is the best, or nothing at all.

Disillusion and despondency are increased proportionally. This generation has witnessed the birth of new infantilism - instant gratification in everything. But, by its very nature, domesticity does not work like that. 'The longer someone has been on their own, the more independent and set in their ways they become, building up an unrealistic picture of what they expect from a relationship,' says Knowles. 'When one discovers the ideal may not exist, that's when crisis strikes. We have to try and find a first better, as opposed to a second best, otherwise life will never move forward.'

So, is flying solo really such a terrible idea? Should we identify our desire to return to domesticity as what it is - the contemporary incarnation of the urge that used to make men buy Harleys, and work it through without giving in to the urge? Should we carry on holding out for the perfect relationship, delaying parenthood in return for the pursuit of a career?

'The history of relationships is like a swinging pendulum,' says Knowles. 'We move from liberal to tight, affluent to Dickensian. But kids in the playground are still playing mums and dads. It's still a good game, which offers a kernel of aspiration: the idea that being in a relationship is a good thing.'

'We're not meant to be on our own; we're a tribal race,' she adds. 'We just have to stop expecting four orgasms a night and become more positive and realistic about what we've got. Only then can life become quite brilliant.' And the modern midlife crisis can become a natural progression.